The fracture behavior of a metallic material is a key factor in determining the suitability of the material for use in structural applications.
Impact testing is a traditional method for studying the fracture behavior of materials. Typically, an impact test specimen of the material is supported in the fixture and struck wit a heavy pendulum to fracture the specimen. The force necessary to fracture the specimen is a measure of the impact absorbing ability of the material. A notch may be introduced into the surface of the impact specimen to concentrate the impact stress and thus increase the severity of the impact test.
Many conventional metals exhibit high impact strength in the unnotched condition but exhibit very severe degradation in impact absorbing ability in the notched condition and may accordingly be characterized as notch-sensitive. Poor impact resistance, and particularly notch sensitivity translates directly into a structural reliability problem and poses a formidable obstacle to the use of an otherwise suitable material in load bearing applications.
What is needed in the art is a metallic article which exhibits high impact strength in both the notched and unnotched condition.